EP 1 997 423 B1 has disclosed a surgical microscope with an illumination arrangement, comprising illumination optics and a light source. Here, a near-axis or coaxial illumination can be obtained with a first illumination beam path and an off-axis illumination can be obtained with a second illumination beam path. Here, an angle of, for example, 2° or 6° is selected between an observation beam path and illumination beam path. Using such a surgical microscope it is possible, inter alia, to carry out cataract surgery. Furthermore, these surgical microscopes, or the illumination arrangements thereof, are embodied in such a way that it is possible in the eye to be examined to generate the red reflex, that is, the lighting up red of the eye pupil in the case of near-axis illumination, which is known per se. Therefore, structures which are transparent per se, for example, of an eye lens to be removed, can be shown. This is realized using either coaxial illumination or a lateral illumination with a simpler setup, for example under an angle of incidence of 2°. As an alternative to a 2° illumination, or in addition thereto, it is also possible that a larger illumination angle, for example, 6°, is demanded so as to obtain even higher contrasting, that is, light/shadow distribution, and, in particular, to spare the macula on the retina if no red reflex is required, as in the case of a corneal transplant.
Furthermore, United States patent application publication 2007/0247691 describes an illumination arrangement for a surgical microscope which, for example, is used in ophthalmic surgery. The illumination arrangement comprises a mirror for deflecting light, wherein the mirror extends over a length region along an optical axis of the illumination arrangement. This means that the plane of the mirror is inclined in relation to the optical axis and the projection of the mirror plane onto the optical axis, as seen in the cross section, has a certain longitudinal extent. The illumination arrangement comprises a light source, which can be made of a matrix, in particular made of organic light-emitting diodes (OLEDs). Depending on which of these very small light sources is activated, it is possible, as seen in a plane perpendicular to an optical axis of the illumination arrangement, to obtain desired illumination geometries, that is, for example, a 2° or 6° illumination. In particular, no mechanical components are required for generating different illumination geometries. However, uniform illumination of an object field or the targeted illumination of a specific portion thereof, that is, for example, of an eye to be operated, is not always ensured in this case.